The present invention relates generally to phased-array sound pickup apparatus, and in particular to a a phased-array sound pickup apparatus having no unwanted back lobe.
A phased-array sound pickup apparatus has been proposed. The apparatus comprises an array of successively arranged microphones having unidirectional directivity or response patterns which are oriented in equal direction. The signals from the individual microphones are coupled through a switching unit to a tapped incremental variable delay line so that incremental delays are introduced to the signals, which are combined at an output terminal in a desired phase relationship. This results in an array's sharp directivity pattern or main front lobe which can be steered in response to a delay control signal applied to the delay line. However, an unwanted back lobe occurs behind the microphone array with the result that it interferes with the wanted signal.